Supplementary device for binocular range finders



Jan. 25, 1938, l o, FREUND` l 2,106,632

SUPPLEMENTARY DEVICE Fo'R BINOCULAR RANGE FINDERs Filed June 5, 1.936 2Sheets-Sheet l y n ven/or:

Janyzs, 193s.

n o. FREUND Y SUPPLEMENTARY DEVICE FOR BINOCULAR RANGE FINDES Filed June5, 1936 2 Sheets-Sheet 2 [nvenfat' Patented las. 25, 193s UNITED STATESPATENT OFFICE SUPPLEMENTARY DEVICE FOR BINOCULAR RANGE FINDERS OttoFreund, Jena, Germany, assignor, by mesne assignments, to Bausch & LombOptical Company, Rochester, York N. I., a corporation of New Claims.

I have led an application in Germany, June 7, 1935 of which thefollowing is a specification.

The invention has reference to binocular rangeiinders of any kind, i. e.especially to rangeiinders 5 in which the Istereoscopic image of adistant object is compared with stereoscopic measuring marks at constantor variable virtual distances, as well as to rangeiinders for comparinginstead of stereoscopic measuringmarks two such space images of anobject as are produced when different rangender bases are used, theseimages being separated from each other in the field of view by a lineparallel to the rangefnder base or overlapping each other. Inrangeiinders of the 10 said kind, the stereoscopic images are very oftensubject to errors. ofheight, which may be due either tothe componentimage of the object viewed in the one rangeilnder eye-piece and thecorresponding mark lying at a height different from that of thecomponent image of the object viewed in the other rangeiinder eye-pieceand the mark corresponding to this other image, or to two heights of thecomponent images of the object diilering from those of the correspondingmarks. This difference very often obtains also in the positions of thecomponent images of the object relative to the component images over.-lapping them or relative to the separatinglines. For the sake ofsimplicity; the following consideration refers only to rang'enders withmeasuring marlm, but it is understood that, in principle, al1 otherrangenders for measuring methods of the said kind are concerned as well.

' Whereas a diierence of height ofthe two component images of the.object does not entail special disadvantages when, in the fields ofview of the twoveye-pieces, the images of the object areat the sameheight as the corresponding marks, .the measuring accuracy is impairedby 40 even very slight diierences of height between the limages of theobject and the corresponding marks, especially when long serialmeasurements are concerned, for which stereoscopic rangenders areespecially suitable. These errors of height can, it is true, bediscarded by means of suitable devices with whichthe rangeflnders aregenerally equipped, but dimculties arise not so much in neutralizingthese errors as in finding them. As'an observer can view in binocularrangeiinders each of the two ocular elds of view by means of one eyeonly, he is compelled to compare these fields separately, one ,after theother, by shutting his one eye and opening-the vother and vice versa. Acomparison of this kind produces incorrect results when the rangeflnderis stationary, and the viewed object, nearly motionless, but effectingthis comparison is entirelyimpossible when, for instance, therangefinder is placed on a moving ship and when the object f,

is a moving aircraft.

'I'he invention concerns a supplementary device to be placed in thepaths of imaging rays .of the eye-pieces of a binocular rangenderequipped with means for neutralizing errors of height. The supplementarydevice permits to find very reliably errors of height and theirmagnitudes, no matter where the rangefinder is mounted and what kind ofobject is concerned. The idea underlying thisl problem is to placebetween the observers eyes and the image planesof the rangender, opticalmeans which so combine the component images viewed by both eyes that oneeye sees these images overlap each other or separated from each other bya separating line parallelto the rangeilnder base. According to theinvention, the problem is solved by providing the device with at leastone reecting syste`m which deleots the pencil of. imaging raysl of oneeye-piece, an optical system combining the pencils of imaging rays ofthe two eye-pieces, and adisplaceable optical system varying thealtitudinal direction of the one of the two pencils of imaging rays. Thedisplaceable optical system may naturally be o', reecting system whichsimultaneously deects the pencil of imaging rays of an eye-piece. Thesimultaneous perception of the images of both fields of view of therangender by one eye permits the Aobserver to nd easily small errors ofheight and to compensate for differences of height of the componentimages of the object relative to the corresponding marks. Thiscompensation of the errors of height in the rangender is eiected by rstmaking the mark images coincide completely asregards height, which iseffected by means of the displaceable optical system, and by thenproviding this coincidence also with respect to the two component imagesof the object by operating the device for neutralizing errors of height.When range'nders without marksare concerned, the'separating lines'parallel to the rangender base or one of the two pairs of componentimages oi' the object are treated in thesame manner as the mark imagesreferred to-above, errors being removed by subsequent adjustment of theimages or the remaining pair of component images of the object.

The accompanying drawings illustrate ve constructional examples of theinvention. 4Figure 1 shows in plan view section the iirst example inconnection with a stereoscopic rangender.

g Figure 2 represents a section through line A-A in. Figure 1. Figures 3and 5 show the second and third examples, respectively, in plan viewsection. Figure 4 represents a section through line B-B in Figure 3, andFigure 6 represents a section through linev C--C in Figure 5. Figures '7and 8 show in plan view sections the fourth and fth examples,respectively, in connection with a stereoscopic rangeiinder.

The iirst constructional example (Figures 1 and 2) is used in connectionwith a stereoscopic rangeiinder having a housing I. At a distance apartwhich corresponds to the base length, the housing I has two windows 2that are in front of pentagonal prisms 3 each of which has oneroofshaped reecting surface. Pencils of light rays entering the windows2 are deviated at right angles by the prisms 3 and directed toobjectives 4, which gather the imaging rays on the ray exit surfaces 5of triangle prisms 6 each of which is provided with a measuring mark 1whose stereoscopic combination provides a stereoscopic mark at a denitevirtual distance. The image planes of the rangefinder which aredetermined by the marks 1,'are viewed by means of adjustable eyepieces8. The rangefinder has a measuring device which consists in the knownmanner of two wedge-shaped prisms I rotatable in opposite senses bymeans of a milled head 9, and of an indicating device consisting of anindex I2 and a division I I representing ranges. The rangeflnder alsocontains a device .for neutralizing errors of height which consists oftwo wedge-shaped prisms vI4 rotatable in opposite senses by means of amilled head I3. The wedge-shaped prisms I0 are ineffective when theirrefractixng edges are horizontal, in contradistinction whereto thewedge-` shaped prisms I4 do not p roduce any effect when theirrefracting edges are vertical.

The supplementary device according to the first constructional examplehas a housing I5 provided with two. windows I6 at a distance apartcorresponding to that of the eye-pieces 8 of the rangeflnder. Behind theleft window I6, a triangle prism I1 is disposed in a mount I8 which isrotatable about a pin I9 and has an arm 20 connected to a tension spring2I against the action of which the arm can be rotated by means ofascre'w 22. Behind the right :window I6 is a glass cube 23 and a`viewing aperture 25 in the housing I5, the glass cube 23 having adiagonal surface 24 which is so silver-plated as to be halftransparent.' j

When the rangefinder is used'and a verification is to be made as towhether there are any errors of height, which may be due for instance todisplacements of the optical part f the'apparatus on account ofvibration, the supplementary device is i so placed behind therangefinder that the windows I6 are infrontA of the eye-pieces 8. Thepaths of the imaging rays of the eye-pieces 8 are thus combined, and theobject images produced by the 'rangefinder are seen by the observerlookinginto the viewing aperture as superposed on each other, deviationsas to height of the object im# ages as well as ofthe images of themarks' 1 being readily recognizable by their differences of A height.Now, the images of the marks 1 are given equal height by rotating thescrew 22 accordingly and, subsequently thereto, an eventual differenceof height of the object images is compensated for by rotating thewedge-shaped prisms I4 by means of the milled-head I3. Thesemanipulations remove errors of height of the kind in which the objectimages assume heights different from those of the marks-1 and,accordingly, the rangender can be use d agai'r'witho'ut thesupplementary device.

The device'according to the second constructional Vexample (Figures 3and 4) h'as a housing 26 .which is provided with two Windows 21. Behindthe left window 21 is disposed a pentagonal 'prism 28 having aroof-shaped reflecting surface,

and behind the right window 21 is a glass cube 29, which combines thelightrays, and a view.

ing aperture 3|, the glass cube 29 being so silverplated as to behalf-transparent. Between the two prisms, an astronomical telescope 32magnilying one time is so mounted in the housing' 26 as to be rotatable,by means of a screw 34, against the pressure of a spring 35 about ahorizontal axis 33 parallel to the entering imaging rays. l

The device according to'the second example is used in the same manner asthat according to the first example, for instance in connection with astereoscopic rangender of the kind represented in Figure l. As, however,the astronomical telescope 32 in the path of the imaging rays completelyreverses the images, there must be used, instead of the prism I1 of the.first example, which has one reecting surface, a prism 28 which, inaddition to the effect produced by the prism I1, reverses the imagescompletely. The

change of direction of the imaging rays emanating from the eye-piece 8,which is necessary for the compensation of height of the two marks 1, iseffected in the device according to the second example by rotating thetelescope 32 about the hori' zontal axis 33 by means of a screw 34,against the pressure of the spring 35. In all other respects, thedetermination and the compensation of errors of height in the rangenderare effected in the manner described with 4reference to the firstexample.

In the device according to the third construcv tional example (Figures 5and 6), two objectives 31 are mounted in a'housing 36 at such a distanceapart as corresponds to the interocular distance of the eye-pieces 8 ofthe rangender. Behind each of the objectives 31 is disposed a triangularprism 38. The objectives 31 have .the same focal length and, on accountof the deflection of rays lagainst the pressure of a spring 45 about apin 46.

Also the device according to this constructional example can be usedwith a rangelnderfor instance accordingA to Figure 1. When lookingthrough the eye-piece 4I, the person using the device sees an imageiield divided by a vertical separating line, namely the edge 36. Bymeans of the eye-pieces 8 and the objectives 31, 4the object imageproduced by the left rangeflnder objective and the left mark 1 areimaged in the -left half of the said field of view, and the object imageof the right objective 4 and the right mark 1 are imaged in the righthalf of the eld of view. To facilitate the adjustment of the mark imagesat equal -height in the field of view of the device, the marks 1 can bemade to consist of a plurality of parts, one of these parts of each markrepresenting a horizontal line and the other parts being rangenger marksof the usual kind at equal distances from the corresponding lies. Whenthe line imagesin the two halves of the field of view are given the sameheight.

by means of the screw 4I, the heights of the marks used for rangendingare made to coincide with each other. The errors of height areneutralized completely by giving the object images of the twohalves ofthe eld of view the same height in the manner described hereinbefore..

' in the plane of the corresponding mark 1. Be'

The device according to the fourth -construcs ences of height of themark images areremoved tional example (Figure '7) is a stationary`supplementary device mounted into a rangeiinder.'

This rangender conforms substantially to the rangender described withreference to the rst example. 'Ihe dierences of the rangefinder showninv Figure 7 from the said other rangeilnder consist in the following.The pentagonal prisms 41 behind the windows 2 have simple reectingsurfaces, and no image-reversing roof surface. There are no triangularprisms 6 but pentagonal prisms 48 on whose ray exit surfaces, whichcoincide with -the focal planes of the objectives 4, are providedmarks 1. The housing I has a ange part 48 the exterior wall 'of whichcontains the adjustable eye-pieces 8. Behind the prisms 48 are disposedobjectives 50 of such focal lengths as lto imagegthe marks 1 in thefront focal planes of 'the'eye-pieces 8. About an axis at right anglesto the rangeiinder base, a housing 52 can be rotated in the part 48 bymeans of a milled head 53. The housing 52 has two windows 54corresponding to the objectives 58. The one of the-windows 54 isprovided with a dispersing lens 55 of such a focal length I that thefront focus of the optical system consisting of this lens 55 and oneobjective 50 lies hind-the lens 55 is disposed a triangle prism 56, andbehind the free window 54, in the housing 52, is a glass cube 51 havinga diagonal surface' 58 which is so silver-plated as to behalf-transparent. 'Ihe housing 52 also has a window 59, whichcorresponds to the glass cube 51, and between the prism 56 and the cube51 a convergent lens 60 is so disposed that, in consideration of thereection on the surface 58, its rear focal plane coincides with thefront focal plane of the eye-pieces 8.

When ranges are to be measured by means of the device, the housing 52 isso turned through the agency of the milled heady 53 that the ray pathfrom the objectives 50 to the eye-pieces 8 remains unobstructed. Theobjectives 50 produce in the front focal planes, of the eye-pieces 8intermediate images of the image planes of the rangender and themarks 1. As this inter'- mediate imaging entails a complete imagereversion, the prisms 41 and 48 are solconstructed that the intermediateimages are erect, as are the images on the ray exit surfaces 5 in thedehousing 52 is so rotated by means of the milled head 53 that ,theimaging rays of the eye-pieces 8 traverse the prisms. 56`and 51. O naccount of the consequent simultaneous displacement of the divergentlens 55 into theleft of these ray paths, the imaging rays emanating asconvergent rays from the left objective 50 are made parallel and thencombined by theconvergent lens 68 to a converging pencil whose point ofconvergencecoincides with the point of convergence of the convergingpencil of imaging rays produced by the right objective 50. Accordingly,the two images of the viewed object aswell as the images of the twomarks 1 overlap each other in the focal plane of the right eye-piece,and undesired differences of height are noticed at once. Differl prismsdo not produce any effect.

by rotating the milled head 53. When these imagesassume the same height,the .differences `of height of the images ofvtheobjectv are' com-vpensated for by operating the rotating wedgeshaped prisms i4.Subsequentlyto the ray paths l from the objectives 58 to the eye-pieces,8 having been made free by rotatingv the head 53. the

means of two rangenndersystems n' of different.

bases. The said rangeinder has a housing y8| with four apertures forentering rays. The two apertures in the left end of the base are coveredby two planoparallel -glass plates'82, 63', and the two apertures in theright end of the baseV are covered by two divergent lenses 84,A whiciare' equal to each other. The housing 8| contains two tubes 58 and 51having in their ends ftelescope' objectives 88, 69 andy 10, 1I;respectively.. Four pentagonal prisms12, 13,'14'and 15,--'

which are provided behind the ray entrance apertures, deect theentering. pencils of imaging rays at right angles intoV thesaidobjectives.`

The `ray pencils are combined by these objectives to object images andso deflected by means of two ray combining systems 18 and .11, each ofwhich consists of a trapeziform-and an imagereversing roof-surfacedtriangle prism,lthat they are in pairs in the front focal plane of twoadjustable eye-pieces 18, 19 in the housing 8l. The light exit aperturesof the trapeziform and the triangle prisms cover the upper and the lowerhalves, respectively, of the ocular fields of view. To each of theinterior tubes 66, 61 is coordinated a device for displacing the one ofthe two imaging ray pencils altitudinally.. These devices consist ofboxes 80, 8i which are displaceably mounted in the interior tubes 86, 61and in which wedge-shaped prisms 82, 83 are so mounted that theirrefracting edges are horizontal. 'Ihe boxes object, pairs ofwedge-shaped prisms 38, 8| are so disposed in the housing 8| as to berotatable in opposite senses. The refracting edges of the wedges 88, 9|are vertical when the wedge-shaped The pairs of wedge-shaped prisms 88,8| are operated by toothed wheels 92, 93 connected to a shaft 34 whichis disposed in the housing 8| and rotatable by means of a milled head95, the two exterior wedge-shaped prisms being rotatable in a sensereverse to-that of the two interior wedgeshaped prisms. The range-ndingdevice of-the apparatus consists of two-convergent lenses 88, 99displaceable in the direction of the rangefinder base by means of a'rack88 and a'toothed wheel 81. These lenses 8888 are disposed behind thedivergent lenses 54, 68 and have such focal lengths that one each of theconvergent and one each oi' the divergent lenses produce the effect of aplano-parallel plate when the optical axes coincide, incontradistinction where- I toothed wheel 91 is coupled to a milled head|00 and provided with a division representing ranges and coordinated toan index |02.

The supplementary device according to the fifth example has a housing|03 with, two ray entrance apertures |04at a'distance apart whichcorresponds to the interocular distance of the eye-pieces 18. Betweenthe aperturesilil is a rotatable bolt |05 for a lens holder |06. In thislens holder, two objectives |01 are so mounted as to lie behind theapertures |04. Small rotations of the bolt |05 entail such displacementsof the objectives |01 at right angles to their optical axes that theincident-pencil of rays is deviated altitudinally. Behind the objectives|01 are disposedpentagonal prisms |08 for deecting the raypencils atright angles into a ray convergingsystem which consists of two triangleprisms |09 and ||0 and whose cemented surface I Il is sjo silver-platedas to be half-transparent. The rear focal planes of the objectives |01coincide' with the front focal plane of an eye-piece H2. The lens holder|06 is rotated by means ,ofta milled head ||3 and a friction wheel III.`j

- when `the device is tp be used, the housing |03 is givenithe positionbehind 'the eye-pieces of the rangefinder, as described with referenceto the first example. As is well known, this rangefinderproduces twostereoscopic images of an object which are so disposed as to be invertedrelatively to each other and separated by a horizontal separating line.'I'he 4sepz'irating, lines are provided by the lower edges of the lightexit apertures of the trapeziform prisms of the systems 16 and 11, andthe inversion of the images is effected by the roof-shaped surfacesofthe triangle prisms of the said systems. The two object imagesproduced by the objectives 60 and 1| furnish the erect, and the twoobject images produced by the objectives 69 and 'l0 furnish the inversestereoscopic image of the object. The ranges are measured by makingl thedisplaceable lenses 9B, 99 produce acoincidence of the two stereoscopicimages. The supplementary device acts as a double telescope which isdisposed bevhind the eye-pieces, 19 of the rangender and in whose fieldof view the two erect as well as the two inverted object `-images of therangeilnder overlap each other. .,By turning the milled head H3, thelensholder |00 is rotated through small angles until the images of thetwo separating lines coincide in the eld of view of the eye-piece H2.Subsequently thereto, the errors of height of the rangeilnder, which areperceived as differences of height of object images over- `lapping eachother, viz, the unequaldistances of the object images from theseparating line, are removed by rotating the milled heads 8 9 and 89 andthus displacing the wedge-shaped prisms 92 and 0 3 until thesedifferences of height have disappeared in the erect as well as in theinverse object images. Differences of height can now exist onlybetweenthe object images of the upvisible in the right eye-piece 19. As soon asthis adjustment is eilected, the rangender is devoid of anyv errors ofheight detrimental to observations and can be usedfor furthermeasurements without the supplementary device.

I claim:

1. A supplementary device for a binocular rangender having a device forremoving errors of height, the said supplementary device comprising ahousing, this housing having two aper.- tures in one side and a thirdaperture in the opposite side, the distance apart of the two first saidapertures corresponding to the interocular distance of the twoeye-pieces of the said rangender, optical means for lateral deflectionof at least the light rays entering through the one of the two rst saidapertures, optical means for combining the two pencils of light raysentering through the two rst said apertures, optical means foraltitudinal deflection of at least the light rays entering through theone of the two iirst said apertures, and mechanical means for displacingthe last said optical means, the said optical means being disposed inthe said housing.

2. In a supplementary device according to claim' l, said optical meanscomprising a reectingsystem for deecting at least .fthe light raysentering through the one of thel two first said apertures, the saidreecting system being disposed in the said housing and rotatable aboutan axis parallel to the axes of the pencils of light rays enteringthrough the two first said apertures.

3. In a supplementary' device according to claim 1, said optical meanscomprising a telescope disposed in the path of the lightrays enteringthe said housing through the' one ofthe two rst said apertures, the saidtelescope magnifying one time. this telescope being disposed in the saidhousing and rotatable about an axis parallel to the axes of the pencilsof light rays entering through the two rst said apertures. f'

4. In a supplementary `device accordingl to claim 1, said optical meanscomprising a telescope system disposed in the fsaid housing, thistelescope system comprising two objectives and a common eye-piece, thesaid objectives being coordinated to the two rst'said apertures in thehousing, the said eye-piecel being coordinated to the said thirdaperture in the housing, at least one of the said objectives in thehousing being rotatable about an axis parallel to the axis of the Aiirstsaid rotatable objective.

5.- In a binocular rangender having a device for removing errors ofheight, a supplementary device mounted in frontvof the two eye-pieces ofthe said rangeiinder, the said supplementary device comprising ahousing,y this housing having two apertures in one side and a thirdaperture in the opposite side, the distance apart of the two first saidapertines corresponding to the interocul lar distance of the twoeye-pieces of the said rangefinder, optical means for lateral deectionoff'fat least the light rays entering through the "one of the two rstsaid apertures, optical means forco'mbining the two pencils of lightrays entering through the two first said apertures, optical means foraltitudinal deilection of at least the light rays entering through theone of -the two ilrst said apertures, and mechanical means fordisplacing the lastsaid optical means, the said optical means being`disposed in the said housing.

'i'ro FREUND.

